Phosphate fluorosurfactants for use in carbon dioxide

ABSTRACT

A method of removing water from a composition of matter comprises contacting a first composition of matter comprising water with a second composition of matter comprising: (1) at least one surfactant comprising at least one phosphate group and (2) a solvent comprising carbon dioxide, wherein at least a portion of the surfactant is soluble in the solvent, such that the at least one surfactant removes at least a portion of the water from the first composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 09/962,385, filed Sep. 25, 2001, now U.S. Pat. No. 6,684,525now allowed and incorporated herein by reference in its entirety, andclaims the benefit of, and incorporates herein by reference in itsentirety, the following U.S. Applications: U.S. Provisional ApplicationNo. 60/235,516, filed Sep. 26, 2000.

FIELD OF THE INVENTION

The present invention generally relates to surfactants that exhibitsolubility in carbon dioxide, and systems utilizing the same.

BACKGROUND OF THE INVENTION

The use of carbon dioxide as a clean, abundant, and tunable solvent ispotentially environmentally beneficial, and accordingly it is beinginvestigated in a number of applications including, for example,cleaning protocols, coatings, and polymer production and processing. Seee.g., Wells, S. L.; DeSimone, J. Angew. Chem. Int. Ed. 2001, 40, 518.Notwithstanding the above potential benefits, carbon dioxide is oftenlimited in that many materials such as water exhibit limited solubilitytherein.

In response to these possible solubility limitations, fluorosurfactantshave been developed to potentially assist in the dispersion of water incarbon dioxide. See e.g., Harrison, K.; Goveas, J.; Johnston, K. P.;O'Rear, E. A. Langmuir 1994, 10, 3536, Johnston, K. P.; Harrison, K. L.;Clarke, M. J.; Howdle, S. M.; Heitz, M. P.; Bright, F. V.; Carlier, C.;Randolph, T. W. Science 1996, 271, 624, Eastoe, J.; Bayazit, Z.; Martel,S.; Steytler, D. C.; Hennan, R. K. Langmuir 1996, 12, 1423, Eastoe, J.;Cazelles, B. M. H.; Steytler, D. C.; Holmes, J. H.; Pitt, A. R.; Wear,T. J.; Heenan, R. K. Langmuir 1997, 13, 6980, Zielinski, R. G.; Kline,S. R.; Kaler, E. W.; Rosov, N. Langmuir 1997, 13, 3934, Eastoe, J.;Downer, A.; Paul, A.; Steytler, D. C.; Rumsey, E.; Penfold, J.; Heenan,R. K. Phys. Chem. Chem. Phys. 2000, 2, 5235, Lee Jr., C. T.; Bhargava,P.; Johnston, K. P. J. Phys. Chem. B 2000, 104, 4448, Lee Jr., C. T.;Johnston, K. P.; Dai, H. J.; Cochran, H. D.; Melnichenko, Y. B.;Wignall, G. D. J. Phys. Chem. B 2001, 105, 3540, and Liu, Z.-T.; Erkey,C. Langmuir 2001, 17, 274. Accordingly, water-in-carbon dioxide (W/C)microemulsions containing appreciable water quantities have beenachieved, allowing for their use in a number of applications such asnanoparticle synthesis, organic reactions, voltammetric measurements,and enzymatic conversions. See e.g., Holmes, J. D.; Bhargava, P. A.;Korgel, B. A.; Johnston, K. P. Langmuir 1999, 15, 6613, Ji, M.; Chen,X.; Wai, C. M.; Fulton, J. L. J. Am. Chem. Soc. 1999, 121, 2631,Jacobson, G. B.; Lee Jr., C. T.; Johnston, K. P. J. Org. Chem. 1999, 64,1201, Ode, H.; Hunt, F.; Kithara, S.; Way, C. M. Anal. Chem. 2000, 72,4738, Lee, D.; Hutchison, J. C.; Demimonde, J. M.; Murray, R. M. J. Am.Chem. Soc. 2001, 123, 8406, Holmes, J. D.; Settler, D. C.; Rees, G. D.;Robinson, B. H. Languor 1998, 14, 6371, and Kane, M. A.; Baker, G. A.;Pander, S.; Bright, F. V. Languor 2000, 16, 4901. W/C systems have alsobeen the subject of computational treatments. See e.g., Satanically, S.;Cui, S. T.; Cummings, P. T.; Cochran, H. D. Languor 1999,15, 5188.

Nonetheless, inspite of any advantages of these systems, there remains aneed in the art for surfactants and systems employing the same thatallow for improved volatilization of various materials in carbondioxide, such as, for example, water.

SUMMARY OF THE INVENTION

In one aspect, the invention provides a method of removing water from afirst composition of matter. The method comprises contacting a firstcomposition of matter comprising water with a second composition ofmatter comprising: (1) at least one surfactant comprising at least onephosphate group and (2) a solvent comprising carbon dioxide, wherein atleast a portion of the surfactant is soluble in the solvent, such thatthe at least one surfactant removes at least a portion of the water fromthe first composition.

In another aspect, the invention provides a method of applying asurfactant to a substrate. The method comprises providing a compositionof matter comprising at least one surfactant comprising (1) at least onephosphate group and (2) a solvent comprising carbon dioxide, wherein atleast a portion of the surfactant is soluble in the solvent; andapplying the composition of matter onto a substrate such that the carbondioxide separates from the surfactant and wherein the surfactant coatsthe substrate.

In another aspect, the invention provides compositions of mattercomprising (1) at least one surfactant comprising at least one phosphategroup and (2) a solvent comprising carbon dioxide.

These and other aspects of the invention are described in greater detailherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a ³¹P NMR spectra of[2-(F-hexyl)ethyl]dimorpholinophosphate before (top) and after (bottom)being solubilized in carbon dioxide;

FIG. 2 illustrates cloud point curves for various phosphate-containingsurfactants;

FIG. 3 illustrates cloud point curves for various phosphate-containingsurfactants;

FIG. 4 illustrates cloud point curves for various phosphate-containinganionic surfactants;

FIG. 5 illustrates cloud point curves for various phosphate-containinganionic surfactants;

FIG. 6 illustrates water uptake for various phosphate-containing anionicsurfactants;

FIG. 7 illustrates water uptake for various phosphate-containing anionicsurfactants;

FIG. 8 illustrates water uptake for various phosphate-containing anionicsurfactants; and

FIG. 9 illustrates water uptake for various phosphate-containing anionicsurfactants.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described below with respect to its preferredembodiments, drawings, and examples. It should be appreciated that thesedo not serve to limit the scope of the invention, but instead illustratethe scope of the invention.

In one aspect, the invention relates to a composition of matter. Thecomposition of matter comprises: (1) at least one surfactant comprisingat least one phosphate group and (2) a solvent comprising carbondioxide.

The surfactant may be illustrated in a number of embodiments. In variousembodiments, the surfactant comprises at least one fluorocarbon group.For the purposes of the invention, the at least one fluorocarbon groupis considered to have an affinity for carbon dioxide, i.e., the at leastone fluorocarbon group is “CO₂-philic”. Preferably, the at least onefluorocarbon group comprises a hydrogen spacer attached to an oxygenatom which is, in turn, attached to the phosphate group.

In various preferred embodiments, the at least one fluorocarbon group isof the formula:C_(m)F_(2m+1)(CH₂)_(n)Owherein m ranges from 1 to 24 and n ranges from 1 to 24.

In other embodiments, the surfactant may further comprise ahydrocarbon-containing group attached to the phosphate group. Inaccordance with the invention, the hydrocarbon-containing group is, incertain embodiments, “CO₂-phobic”, does not have affinity for carbondioxide. Nonetheless, it should be appreciated that when present inbranched form, the hydrocarbon-containing group may be useful fordispersing charged surfactants in CO₂. See Eastoe et al. Journal of theAmerican Chemical Society; 2001; 123(5); 988–989.

In a preferred embodiment, the hydrocarbon-containing chain is of theformula:C_(m)H_(2m+1)Owherein m ranges from 1 to 24.

In various embodiment, the surfactant may be present as an anionicsurfactant. Non-limiting examples of anionic surfactants are of theformulas (VIII) and (IX) as well as others set forth in detailhereinbelow:

wherein R is a branched or straight chained hydrocarbon (e.g.,C_(n)H_(2n+1), wherein n ranges from 1 to 24) orhydrocarbon/fluorocarbon group and M is a countercation such as, forexample, K⁺, Na⁺, or NH₄ ⁺.

In certain embodiments, the surfactants may be present in the form ofhybrid surfactants. For the purposes of the invention, the term “hybridsurfactant” is defined as a surfactant having at least one fluorocarbongroup and at least one hydrocarbon-containing group. Examples of theseare of the formulas (X), (XI), and (XI′): As set forth below, the hybridsurfactants also encompass anionic surfactants in various embodiments.

wherein R_(H) may be independently selected and is a branched orstraight-chained hydrocarbon group (e.g., C_(n)H_(2n+1) wherein n rangesfrom 1 to 24). R_(H) is preferably C₈H₁₇ or C₁₄H₂₉. In anotherembodiment, R_(H) may contain a fluorocarbon group such as, for example,C_(n)H_(2n+1)(CH₂)_(m) wherein n ranges from 1 to 24 and m ranges from 1to 24. R_(F) is independently selected and is a branched or straightchained fluorocarbon group (e.g., hydrocarbon/fluorocarbon group) (e.g.,C_(n)H_(2n+1)(CH₂)_(m) wherein n ranges from 1 to 24 and m ranges from 1to 24 ) wherein M⁺ is a countercation such as, for example, K⁺, Na⁺, orNH₄ ⁺. Preferred groups for R_(H) are, without limitation, C₆F₁₃(CH₂)₂and C₁₀F₂₁(CH₂)₂ and preferred groups for R_(H) are, without limitation,C₄H₉, C₈H₁₇, C₁₂H₂₅, and C₁₆H₃₃. X_(I) is a functional group such ashydroxy (—OH), alkyl, (such that a phosphate bond is formed) and aphosphoamide groups (such as, for example, piperidine, morpholine, andthe like). In one preferred embodiment, when M⁺ is NH₄ ⁺, R_(F) andR_(H) are each independently selected and preferably range fromC₂F₅(CH₂)₂ to C₈F₁₇(CH₂)₂.

Another preferred anionic surfactant according to the present inventionis of the following formula:

wherein R_(F) ranges from CF₃(CH₂)_(n) to C₂₄F₄₉(CH₂)_(n) wherein nranges from 1 to 24. In other embodiments, the surfactant may be presentin the form of a cationic surfactant. Examples of cationic surfactantsare, without limitation, those represented by the formulas (VI) and(VII) (e.g., piperazinium phosphates):

wherein R may be a branched or straight chained hydrocarbon group (e.g.,C_(n)H_(2n+1) wherein n ranges from 1 to 24) or ahydrocarbon/fluorocarbon group including, for example,C_(n)H_(2n+1)(CH₂)_(m) wherein n ranges from 1 to 24 and m ranges from 1to 24, and X is a counteranion which may be a halogen (e.g., chloride,bromide), triflate, or “BarF” (anion of Kobayashi's reagent as set forthbelow):

As an example, one or more morpholine units may be attached to thephosphate group. Embodiments represented by formulas (I) through (V) and(IX) and (X) describe such structures. Moreover, certain embodimentsillustrate at least one fluorocarbon-containing group attached to thephosphate group. In one example, a fluorocarbon group is attached to ahydrocarbon spacer (e.g., 1 to 12 methylene units long) which is in turnattached to an oxygen atom and then the phosphorous atom as illustrated.

wherein m and n are each independently selected with m ranging from 1 to24 and n ranging from 1 to 24. In a preferred embodiment, with respectto formula (I), m may be 6, 8, or 10, and n is 2. In a preferredembodiment, with respect to formula (II), m may be 6 or 8 and n is 2.

Hydrocarbon analogs of formulas (III) through (IV) are also encompassed.

wherein m is independently selected and ranges from 1 to 24. Preferably,m is 10.

Hybrid morpholine-containing surfactants can also be employed and are ofthe formula:

wherein x ranges from 1 to 24, m ranges from 1 to 24, and n ranges from1 to 24. In a preferred embodiment, x is 8, m is 6, and n is 2.

The surfactants are believed to be potentially capable of reversemicelle and/or water-in carbon dioxide emulsion (i.e., microemulsion)formation. In certain embodiments, such compositions containing watermay be present as homogeneous fluids or phases. Accordingly, in anotheraspect the invention provides a reverse micelle that comprises thecomposition of matter as defined herein and water. For the purposes ofthe invention, the term “reverse micelle” is defined as a micelle inwhich a water component is on the inner portion of the micelle. Thus,the “hydrophilic” segment of each surfactant present in the reversemicelle is on the inner portion of the micelle, while the “CO₂-philic”segment of each surfactant is on the outer portion of the micelle. As aresult, the surfactants are useful in a number of applications. Forexample, the reverse micelles may be capable of encapsulating a numberof pharmaceutically active agents therein, the selection of which isknown to one skilled in the art. In other various embodiments, thesurfactants can also be employed in cleaning or water removal inapplications such as CO₂-based lithography, wherein a relatively smallamount of water used in development can be dissolved and “swept away”into the phase containing predominantly carbon dioxide as well assynthesizing nanoparticles within microemulsion water pools. Organic(i.e. polymers) and inorganic nanoparticles can be also prepared usingmicroemulsion water pools as reactors/templates. The surfactants canalso be used in extraction applications, e.g., metal extractions fromaqueous solutions.

Various amounts of water may be taken-up by the compositions of matterand methods of the present invention. For example, in one embodiment,the amount of water may range from above about 0, 5, 10, 20, 30, or 40to about 60, 70, 80, 90, 95, 100, 150, or 200 percent based on theweight of the surfactant. More specifically, in accordance with theinvention, the surfactant is capable of taking up 100 percent of its ownweight in the form of water.

For the purposes of the invention, carbon dioxide is employed in aliquid or supercritical form. The composition of matter typicallyemploys carbon dioxide as a continuous phase, with the composition ofmatter preferably comprising from about 50, 60, or 75 weight percent toabout 80, 90, or 99 weight percent of carbon dioxide. If liquid CO₂ isused, the temperature employed during the process is preferably below31° C. In one preferred embodiment, the CO₂ is utilized in a“supercritical” phase. As used herein, “supercritical” means that afluid medium is at a temperature that is sufficiently high that itcannot be liquefied by pressure. The thermodynamic properties of CO₂ arereported in Hyatt, J. Org. Chem. 49: 5097–5101 (1984); therein, it isstated that the critical temperature of CO₂ is about 31° C. Inparticular, the methods of the present invention are preferably carriedout at a temperature range from about 20° C. to about 60° C. Thepressures employed preferably range from about 1000 psia (6.9 MPa) toabout 5500 psia (37.9 MPa).

The composition of matter may also comprise components in addition tothose described above. Preferably, these components do not react withthe surfactant. Exemplary components include, but are not limited to,polymer modifier, water, rheology modifiers, plasticizing agents,antibacterial agents, flame retardants, and viscosity reductionmodifiers. Co-solvents and co-surfactants may also be optionallyemployed. These components may be used if they do not react with thereactive functional polymer.

Exemplary co-solvents that could be used include, but are not limitedto, alcohols (e.g., methanol, ethanol, and isopropanol); fluorinated andother halogenated solvents (e.g., chlorotrifluoromethane,trichlorofluoromethane, perfluoropropane, chlorodifluoromethane, andsulfur hexafluoride); amines (e.g., N-methyl pyrrolidone); amides (e.g.,dimethyl acetamide); aromatic solvents (e.g., benzene, toluene, andxylenes); esters (e.g., ethyl acetate, dibasic esters, and lactateesters); ethers (e.g., diethyl ether, tetrahydrofuran, and glycolethers); aliphatic hydrocarbons (e.g., methane, ethane, propane, butane,n-pentane, and hexanes); oxides (e.g., nitrous oxide); olefins (e.g.,ethylene and propylene); natural hydrocarbons (e.g., isoprenes,terpenes, and d-limonene); ketones (e.g., acetone and methyl ethylketone); organosilicones; alkyl pyrrolidones (e.g., N-methylpyrrolidone); paraffins (e.g., isoparaffin as well as other alkanes andparaffin waxes); petroleum-based solvents and solvent mixtures; and anyother compatible solvent or mixture that is available and suitable.Mixtures of the above co-solvents may be used.

Exemplary co-surfactants that may possibly be used include, but are notlimited to, longer chain alcohols (i.e., greater than or equal to C₈)such as octanol, decanol, dodecanol, cetyl alcohol, laurel alcohol, andthe like; and species containing two or more alcohol groups or otherhydrogen bonding functionalities; amides; amines; and other likecomponents. Suitable other types of materials that are useful asco-surfactants are well known by those skilled in the art, and may beemployed in the composition of matter of the present invention. Mixturesof the above may be used.

The invention also provides a method of the separating the surfactantfrom the carbon dioxide and applying the surfactant to a substrate. Inparticular, the method comprises providing a composition of mattercomprising at least one surfactant comprising (1) at least one phosphategroup and (2) a solvent comprising carbon dioxide, wherein at least aportion of the surfactant is soluble in the solvent; and applying thecomposition of matter onto a substrate such that the carbon dioxideseparates from the surfactant and wherein the surfactant coats thesubstrate. Techniques for separating and applying materials to asubstrate are known in the art and are described, for example, in U.S.Pat. No. 5,863,612 to DeSimone et al., the disclosure of which isincorporated herein by reference in its entirety, such as found on col.5, line 47 through col. 6, line 11. Examples of methods for separatingthe surfactant include, without limitation, boiling off the carbondioxide and leaving the surfactant behind, and precipitation of thesurfactant into a non-solvent either by introducing a non-solvent to avessel or reactor containing the surfactant or the transfer of thevessel or reactor contents to another vessel containing a non-solventfor the surfactant. In one embodiment, the separation and applicationsteps may be carried out together and include, as an example, passing(e.g., spraying or spray-drying) a solution containing the surfactantthrough an orifice to form particles, powder coatings, fibers, and othercoatings on the substrates. A wide variety of substrates may be employedsuch as, without limitation, metals, organic polymers, inorganicpolymers, textiles, and composites thereof. Exemplary substratesinclude, without limitation, integrated circuits, silicon wafers,silicon wafers with vias containing water, low-dielectric constantsurfaces used as interlayer dielectrics on integrated circuits, a MEM, aporous material, a micro-porous material, a nano-porous material, anon-woven material, surfaces to be cleaned, surfaces to be treated withpassivation layers, surfaces to be coated, surfaces to be treated with aself-assembled monolayer (“SAM”), photoresist coated surfaces, opticalinterfaces, optical relays, optical fibers, metallized surfaces, andmicromirrors. These application techniques are demonstrated for liquidand supercritical solutions. The surfactant may form a low surfaceenergy coating on the substrate. Examples of embodiments of substratesinclude, without limitation, textiles, papers, fiber optics, as well asother surfaces.

The compositions of matter, and in particular the surfactant, are usefulin a number of applications such as, but not limited to, cleaningprocesses, solvent pool formation for polymerization processes,inorganic particle synthesis, and enzymatic reactions.

The composition of matter may include various amounts of surfactant. Ina preferred embodiment, the composition of matter comprises from about1, 2, 5, or 7 to about 5, 8, 10, 15, or 20 percent by weight ofsurfactant.

In another aspect, the invention provides a method of removing waterfrom a composition of matter. The method comprises contacting a firstcomposition of matter comprising water with a second composition ofmatter comprising: (1) at least one surfactant comprising at least onephosphate group and (2) a solvent comprising carbon dioxide, wherein atleast a portion of the surfactant is soluble in the solvent, such thatthe at least one surfactant removes at least a portion of the water fromthe first composition.

Embodiments describing the second composition of matter comprising thesurfactant are set forth hereinabove, as well as for the solventcomprising carbon dioxide. In a preferred embodiment, the secondcomposition of matter may be present as a homogeneous phase prior to andafter contacting the first composition of matter, although otherembodiments may also be contemplated, i.e., the second composition ofmatter may be heterogeneous.

The first composition of matter comprising water may be present in theform of a number of embodiments, such as, for example, various articlesof manufacture. Examples of such embodiments include, withoutlimitation, integrated circuits, silicon wafers, silicon wafers withvias containing water, low-dielectric constant surfaces used asinterlayer dielectrics on integrated circuits, a MEM, a porous material,a micro-porous material, a nano-porous material, a non-woven material,surfaces to be cleaned, surfaces to be treated with passivation layers,surfaces to be coated, surfaces to be treated with a self-assembledmonolayer (“SAM”), photoresist coated surfaces, optical interfaces,optical relays, optical fibers, metallized surfaces, and micromirrors.

Methods for carrying out water removal may be conducted in systems,vessels, cells, and apparatuses known to one skilled in the art. Suchsystems, vessels, cells, and apparatuses include, without limitation,those capable of withstanding high pressure. Such equipment may beoptionally contain agitation and heating means, the selection of whichis known. The methods of water removal may be carried out by employingbatch, continuous, and semi-continuous systems.

The surfactants that are employed in the invention may be formed byvarious techniques such as, for example, as set forth in Sadtler, V. M.;Jeanneaux, F.; Krafft, M. P.; Rábai, J.; Riess, J. G. New Journal ofChemistry. 1998, 609. Other synthesis routes may also be used. As anexample, morpholinosurfactants having fluorocarbon units attachedthereto may be formed by first phosphorylation of a fluorinated alcoholby phosphorus oxychloride in the presence of N(CH₂CH₃)₃ and (CH₃CH₂)₂O.In one embodiment, the formation of di- and triesters and thechlorination of the alcohol can potentially be avoided by using dryether and an excess of triethylamine, which results in the precipitationof triethylammonium chloride.(Perfluoroalkyl)alkyldimorpholinophosphates are subsequently obtainedobtained by a reaction with morpholine. The synthesis ofbis[(F-alkyl)alkyl]monomorpholinophosphates also may involve the directphosphorylation of F-alkylated alcohols by OPCl₃, followed by reactionwith morpholine as described in Sadtler, V. M., et al.

Piperazine surfactants may be made by following the teachings ofKatritzky, A. R., Davis, T. L., Rewcastle G. W., Rubel, G. O., and Pike,M. T., Langmuir 1988 4, 732–735. In accordance with the teachings setforth in Katritzky, et al., the following synthesis path may be followedfor forming sulfonyl piperazinium compounds:

It is believed that one can form piperazinium phosphate surfactants bysubstituting N-methylpiperazine for morpholine in the synthetic pathwayutilized for morpholinophosphate surfactant synthesis. The methylatednitrogen can then be quaternized by iodomethane to provide one variantof the desired compounds. An exemplary synthesis route is given below.

An embodiment illustrating a synthesis route for hybrid surfactants isillustrated according to the following scheme:

Neutral or anionic surfactants may be formed according to the aboveembodiment. It should be appreciated that these surfactants may beformed by other synthesis route. In the above synthesis route, R_(H) isC_(m)H_(2m+1) wherein m ranges from 1 to 24 and R_(F) may beC_(n)F_(2n+1) wherein n ranges from 1 to 24.

Various processing conditions (e.g., time and temperature) may beemployed in the above method. In one embodiment, for example, steps 1and 2 can take place at a temperature ranging from about 0° C. to about10° C. with warming to room temperature for about 6 to about 12 hoursunder an inert atmosphere (e.g., nitrogen or argon). Steps 3 and 4 takeplace under ambient conditions. The above synthesis employs equipmentand techniques known in the art such as conventional glass round bottomflasks and stir bars. Other types of equipment can also be employed.

The following examples are intended to illustrate the present invention,and are not intended to limit the scope of the invention. In theexamples, the morpholinophosphate surfactants were prepared as describedin Sadtler, V. M. et al. These compounds were purified by silica gelchromatography.

The anionic phosphate surfactants were synthesized by adapting knownmethods for preparing phosphates with fluorinated chains (see Kraft,M.-P.; Rolland, J.-P.; Vierling, P.; Riess, J. G. New Journal ofChemistry 1990, 14, 869.) and forming the sodium salt via neutralizationin ethanol (see Romsted, L. S.; Zanette, D. J. Phys. Chem. 1988, 92,4690.). The compounds exhibited the expected 1H, 19F, and 31P NMRspectral patterns and also possessed adequate purity as determined byelemental analysis (Atlantic Microlabs, Norcross, Ga.), i.e., defined asgenerally within 0.3% of the expected calculated analytical elementalpercentages.)

Cloud point solubilities of surfactants and surfactants and water incarbon dioxide were carried out using a HIP variable volume pressuregenerator/view cell (maximum volume=15 mL) containing a 0.5 inch thicksapphire window for viewing and a magnetic stir bar to agitate thesolution. CO₂ was injected with the aid of an ISCO compression pumpconnected to the cell through high-pressure steel tubing. The cell wasfurther attached to a Sensotec pressure transducer and an Omegathermocouple for pressure and temperature readouts, respectively.Measured amounts of surfactant and water were added at room temperatureprior to pressurization with CO₂. Samples were heated (controlled to±0.1° C.) in the cell through the use of variac-controlled heating tape.Cloud points (judged as the reversible onset of a visually fully opaquesolution) were taken on the cooling cycle by isothermally varying thepressure through volume changes facilitated by the hand-controlledpiston. The cell was tipped at a downward angle to aid in theobservation of any phase-separated liquids. The cell was cleanedthoroughly between experiments.

UV-Vis spectra were acquired using a Perkin Elmer Lambda 40spectrometer. Pressurized solutions were prepared in a 2.5 mL stainlesssteel cell, equipped with two 1 in. diameter×⅝ in. thick sapphirewindows enclosing a 1 cm solution path length. Appropriate amount ofsurfactant and water were placed into the cell chamber, along with a ¼in. magnetic stir bar for agitation. A film of methyl orange (for aconcentration of 5×10⁻⁵ M) was pre-cast and dried on one of the sapphirewindows by addition of a stock solution via syringe. The chamber wastightly sealed, and the cell was pressurized and stirred until a clear,one-phase solution was present.

EXAMPLES 1–7 CO₂ Solubility Evaluation

The CO₂ solubility of the surfactants was carried out using a stainlesssteel view cell (2.5 mL internal volume) specially designed for highpressure studies. CO₂/surfactant solutions were held within two sapphireglass windows (sealed with Teflon® o-rings) which were, in turn, held inplace by threaded steel caps fit to brass washers. Attached to the cellwere steel tubings for injecting CO₂ and for venting the system, as wellas a thermocouple and transducer to monitor internal temperature andpressure, respectively. CO₂ was transferred to the cell by way of anISCO single pump compressor. A ¼ inch magnetic bar was included to stirsolutions. The chamber temperature could be raised with the aid ofvariac-controlled heating elements.

Experiments involved adding weighed amounts of the surfactants into thechamber along with the stir bar, tightly sealing the chamber, andinjecting CO₂ to pressures between 1000 and 1500 psig at roomtemperature. The solutions were stirred and the temperatures increasedat a rate of approximately 1° C./minute. Temperatures, pressures, andsolution appearances were recorded. The results are listed in Table 1.The fluorosurfactants were soluble (i.e, dissolved in clear, transparentsolutions) at concentrations of 10 percent (w/v) over temperatures up to60° C., and exhibited no cloud points. Hydrocarbon analogs also provedto be soluble over similar pressure and temperature ranges.

TABLE 1 Solubilities of Morpholinophosphate Surfactants in Dense CO₂(2.5 mL volume) Weight of Pressure Sample Temperature Range Surfactant(g) Range (° C.) (psig) Solubility 1 0.304 24–60 1070–2360 ClearSolution 2 0.298 24–53 1050–1820 Clear Solution 3 0.253 23–60 1100–2500Clear Solution 4 0.259 25–59 1010–1760 Clear Solution 5 0.258 25–591070–2100 Clear Solution 6 0.253 23–59 1270–2960 Clear Solution 7 0.13924–59 1250–2860 Clear Solution

EXAMPLE 8 Synthesis of Bis-[2-(F-hexyl)ethyl]phosphate, sodium salt

Bis-[2-(F-hexyl)ethyl]phosphate, sodium salt was synthesized accordingto the following example. Phosphorous oxychloride (5.27 g, 34.3 mmol)was added via syringe to 200 mL anhydrous diethyl ether, under nitrogen.The mixture was cooled to 0° C., and a solution of1H,1H,2H,2H-perfluorooctanol (25 g, 68.7 mmol) and triethylamine (17.4g, 172 mmol) in 100 mL diethyl ether was slowly added, leading to theformation of white precipitate. The solution warmed to room temperatureand was allowed to stir further under nitrogen overnight. The resultingwhite solid (triethylamine hydrochloride salt) was filtered and washedwith 100 mL diethyl ether. The solvent and excess triethylamine wasremoved via rotary evaporation, providing an orange oil which wasdissolved in 100 mL acetonitrile and 5 mL water. Two layers ofimmiscible liquids resulted, and the lower layer was isolated and driedunder rotary evaporation. 22.5 g of crude as a viscous orange oil wasprovided. The oil was taken up in 100 mL ethanol. 2.28 g of NaOH (50 wt.% in water, 28.5 mmol NaOH) solution dissolved in 20 mL ethanol wasslowly added. The solution precipitated into a gel, which was allowed tostir overnight. A white sticky solid (˜3 g) was filtered and discarded,and the filtrate was concentrated via rotary evaporation andprecipitated with diethyl ether. The resulting solid was dried and thentaken up in 100 mL, and 1 g decolorizing carbon was added to thesolution. This resulting solution was briefly stirred. The carbon wasfiltered off and solvent evaporated. 14.9 g (53%) of the desired productafter vacuum drying was provided (mp>220° C.).

¹H NMR: (300 MHz: δ, CH₃OD) 4.13 (q, 4H; J_(HH): 6.6 Hz, J_(HP): 6.8 Hz;CH₂O), 2.55 (tt, 4H; J_(HH): 6.6 Hz, J_(HF): 19.2 Hz; CF₂CH₂) ¹⁹F NMR:(282 MHz: δ, CH₃OD) −83.0 (CF₂CF₃), −115.1 (CH₂CF₂), −123.2, −124.2,−125.0, (3×CF₂), −127.7 (CF₂CF₃) ³¹P NMR: (121 MHz: δ, CH₃OD) −0.65 ppmAnal. Calcd.: C, 23.66; H, 0.99. Found: C, 23.46; H, 1.00.

EXAMPLE 9 Synthesis of [2-(F-decyl)ethyl]octylphosphate, sodium salt

2-(F-decyl)ethyl]octylphosphate, sodium salt was synthesized as follows.Phosphorous oxychloride (1.3 g, 8.6 mmol) was added via syringe to 25 mLanhydrous diethyl ether, under argon. The mixture was cooled to 0° C.,and a solution of 1H,1H,2H,2H-perfluorododecanol (4.65 g, 8.2 mmol) andtriethylamine (2.1 g, 20.8 mL) in 25 mL diethyl ether was slowly added.A white precipitate then formed. The mixture was stirred for 1 h at 0°C., and a solution of 1-octanol (1.1 g, 8.2 mmol) and triethylamine (2.1g, 20.8 mL) in 25 mL diethyl ether was added to the solution, resultingin the formation of more white precipitate. The solution was allowed tocome to room temperature and was stirred under argon overnight. Thewhite solid (triethylamine hydrochloride salt) was filtered and thefiltrate was condensed via rotary evaporation and dissolved in a 20 mLmixture of acetonitrile and chloroform (19/1). 1 mL of water was slowlyadded and the solution was stirred overnight, providing a white solid,which was washed with acetonitrile and filtered. The solid wastriturated in chloroform, the insoluble material filtered away, and thechloroform removed via rotary evaporation to provide 3.0 g of theneutral phosphate (48.4 percent) The corresponding sodium salt wasprepared in quantitative yield via neutralization with 1 equivalent ofsodium hydroxide in ethanol (mp >225° C.).

¹H NMR: (300 MHz: δ, CH₃OD) 4.14 (q, 2H; R_(F) chain CH₂O), 3.84 (q, 2H;R_(F) chain CH₂O), 2.55 (m, 2H; CF₂CH₂), 1.6 (m, 2H; CH₂CH₂CH₂O),1.2–1.4 (m, 10H), 0.88 (t, 3H; J_(HH): 7.1 Hz) ¹⁹F NMR: (282 MHz: δ,CH₃OD) −81.4 (CF₂CF₃), −113.3 (CH₂CF₂), −121.4, −122.4, −123.4, (7×CF₂),−126.0 (CF₂CF₃) ³¹P NMR: (121 MHz: δ, CH₃OD) 1.53 Anal. Calcd.: C,30.86; H, 2.72. Found: C, 30.73; H, 2.62.

EXAMPLE 10 Synthesis fDi-Fluoro-Chained Analog Surfactant

Di-fluoro chained analog surfactants were formed according to thefollowing synthesis route:

EXAMPLE 11 Cloud Point Evaluation

The solubilities of various surfactants of the formula described belowwere evaluated in carbon dioxide:

wherein R_(H) is C₄H₉ (“8-4”), C₈H₁₇ (“8—8”), C₁₂H₂₅ (“8-12”), andC₁₆H₃₃ (“8-16”). Cloud point curves for these surfactants are set forthin FIG. 2.

EXAMPLE 12 Cloud Point Evaluation

The solubilities of various surfactants of the formula described belowwere evaluated in carbon dioxide:

wherein R_(H) is C₄H₉ (“12-4”), C₈H₁₇ (“12-8”), and C₁₂H₂₅ (“12—12”).Cloud point curves for these surfactants are set forth in FIG. 3.

EXAMPLE 13 Cloud Point Evaluation (Anionic Surfactant)

The solubility of an anionic surfactant of the formula described belowwas evaluated in carbon dioxide:

wherein R_(H) is C₄H₉ (“8-4”). A cloud point curve for this surfactantis set forth in FIG. 4.

EXAMPLE 14 Cloud Point Evaluation (Anionic Surfactants)

The solubility of an anionic surfactant of the formula described belowwas evaluated in carbon dioxide:

wherein R_(H) is C₄H₉ (“12-4”) and C₈H₁₇ (“12-8”). A cloud point curvefor this surfactant is set forth in FIG. 5.

EXAMPLE 15 Water Uptake Evaluation (Anionic Surfactant)

The water uptake capability of an anionic surfactant was evaluatedwherein the surfactant is of the formula:

wherein R_(H) is C₄H₉ (“12-4”).

The concentration of surfactant in carbon dioxide was 2.5 weightpercent. The results are set forth in FIG. 6.

EXAMPLE 16 Water Uptake Evaluation (Anionic Surfactants)

The water uptake capability of an anionic surfactant was evaluatedwherein the surfactant is of the formula:

wherein R_(H) is C₄H₁₇ (“12-8”).

The concentration of surfactant in carbon dioxide was 2.5 weightpercent. The results are set forth in FIG. 7.

EXAMPLE 17 Water Uptake Evaluation (Anionic Surfactants)

The water uptake capability of an anionic surfactant was evaluatedwherein the surfactant is of the formula:

wherein R_(H) is C₁₂H₂₅ (“12—12”).

The concentration of surfactant in carbon dioxide was 2.5 weightpercent. The results are set forth in FIG. 8.

EXAMPLE 18 Water Uptake Evaluation (Anionic Surfactants)

The water uptake capability of an anionic surfactant was evaluatedwherein the surfactant is of the formula:

The concentration of surfactant in carbon dioxide was 2.5 weightpercent. The results are set forth in FIG. 9.

In the specification, drawings, and examples there have been disclosedtypical preferred embodiments of the invention and, although specificterms are employed, they are used in a generic and descriptive senseonly and not for the purposes of limitation, the scope of the inventionbeing set forth in the following claims.

1. A composition of matter comprising: at least one anionic surfactantcomprising at least one phosphate group, wherein the anionic surfactantis represented by the formula:

wherein R_(H) is C_(n)H_(2n+1) wherein n ranges from 1 to 24 orC_(n)F_(2n+1)(CH₂)_(m) wherein n ranges from 1 to 24 and m ranges from 1to 24; wherein R_(F) is C_(n)F_(2n+1) (CH₂)_(m) wherein n ranges from 1to 24 and m ranges from 1 to 24; and wherein M is selected from thegroup consisting of K⁺, Na⁺, and NR⁴⁺, wherein R is selected form thegroup consisting of H, CH₃, C₆H₅, or a combination thereof; and asolvent comprising liquid or supercritical carbon dioxide, wherein atleast a portion of the surfactant is soluble in the solvent.
 2. Thecomposition of matter according to claim 1, wherein: R_(F) is selectedfrom the group consisting of C₆F₁₃(CH₂)₂ and C₁₀F₂₁(CH₂)₂; R_(H) isselected from the group consisting of C₄H₉, C₈H₁₇, C₁₂H₂₅, and C₁₆H₃₃;and M is selected from the group consisting of Na⁺ and NR⁴⁺, wherein Ris H, CH₃, C₆H₅, or a combination thereof.
 3. The composition of matteraccording to claim 1, wherein the carbon dioxide is supercritical carbondioxide.
 4. The composition of matter according to claim 1, wherein thecarbon dioxide is liquid carbon dioxide.
 5. The composition of matteraccording to claim 1, wherein said surfactant is present in saidcomposition of matter in an amount ranging from about 1 to about 10percent based on the weight of the surfactant.
 6. The composition ofmatter according to claim 1, further comprising at least one additionalcomponent selected from the group consisting of polymer modifiers,rheology modifiers, plasticizing agents, antibacterial agents, flameretardants, viscosity reduction modifiers, co-solvents, andco-surfactants.
 7. The composition of matter according to claim 1,wherein the composition of matter comprises water.
 8. A reverse micellecomprising the composition of matter of claim
 7. 9. The reverse micelleof claim 8, wherein the water is present in an amount ranging from aboveabout 0 to about 200 percent based on the weight of the surfactant. 10.A composition of matter comprising: at least one cationic surfactantcomprising at least one phosphate group; and a solvent comprising liquidor supercritical carbon dioxide, wherein at least a portion of thesurfactant is soluble in the solvent.
 11. The composition of matteraccording to claim 10, wherein the cationic surfactant is selected fromthe group consisting of:

wherein R is selected from the group consisting of C_(n)H_(2n) ₁;wherein n ranges from 1 to 24 and C_(n)F_(2n+1)(CH₂)_(m), wherein nranges from 1 to 24 and m ranges from 1 to 24; and wherein X is acounteranion selected from the group consisting of halogen, triflate,and


12. The composition of matter according to claim 10, wherein the carbondioxide is supercritical carbon dioxide.
 13. The composition of matteraccording to claim 10, wherein the carbon dioxide is liquid carbondioxide.
 14. The composition of matter according to claim 10, whereinsaid surfactant is present in said composition of matter in an amountranging from about 1 to about 10 percent based on the weight of thesurfactant.
 15. The composition of matter according to claim 10, furthercomprising at least one additional component selected from the groupconsisting of polymer modifiers, rheology modifiers, plasticizingagents, antibacterial agents, flame retardants, viscosity reductionmodifiers, co-solvents, and co-surfactants.
 16. The composition ofmatter according to claim 10, wherein the composition of mattercomprises water.
 17. A reverse micelle comprising the composition ofclaim
 16. 18. The reverse micelle of claim 17, wherein the water ispresent in an amount ranging from above about 0 to about 200 percentbased on the weight of the surfactant.
 19. A composition of mattercomprising: at least one surfactant comprising at least one phosphategroup, wherein the at least one surfactant comprises one or moremorpholine units attached to the at least one phosphate group; and asolvent comprising liquid or supercritical carbon dioxide, wherein atleast a portion of the surfactant is soluble in the solvent.
 20. Thecomposition of matter according to claim 19, wherein the surfactant isselected from the group consisting of

wherein m and n are independently selected with m ranging from 1 to 24and n ranging from 1 to 24; wherein x ranges from 1 to 24; wherein M isselected from the group consisting of K⁺, Na⁺, and NH₄ ⁺; wherein R isC_(p)H_(2p+1), and p ranges from 1 to 24; wherein R_(F) isC_(p)F_(2n+1), and n ranges from 1 to 24; and wherein R_(H) is either:(1) C_(n)H_(2n+1), wherein n ranges from 1 to 24, or (2)C_(n)F_(2n+1)(CH₂)_(m) wherein n ranges from 1 to 24 and m ranges from 1to
 24. 21. The composition of matter according to claim 19, wherein thecarbon dioxide is supercritical carbon dioxide.
 22. The composition ofmatter according to claim 19, wherein the carbon dioxide is liquidcarbon dioxide.
 23. The composition of matter according to claim 19,wherein said surfactant is present in said composition of matter in anamount ranging from about 1 to about 10 percent based on the weight ofthe surfactant.
 24. The composition of matter according to claim 19,further comprising at least one additional component selected from thegroup consisting of polymer modifiers, rheology modifiers, plasticizingagents, antibacterial agents, flame retardants, viscosity reductionmodifiers, co-solvents, and co-surfactants.
 25. The composition ofmatter according to claim 19, wherein the composition of mattercomprises water.
 26. A reverse micelle comprising the composition ofmatter of claim
 25. 27. The reverse micelle of claim 26, wherein thewater is present in an amount ranging from above about 0 to about 200percent based on the weight of the surfactant.